The cluster communication service is a half-duplex two-way service, and realizes the one-to-more service. The characteristic of the cluster user is that one user is speaking and one or more users are listening. After the users who need to speak initiate a request for speaking right, the network determines who can get the speaking right according to a certain seizing policy; the user who gets the speaking right becomes the speaking user, and other users in the cluster group become the listening users. Thus, it can vary repeatedly to let the users in the group speak and communicate, until the cluster call is over.
On the basis of the above-mentioned characteristic of the cluster, during the process of one cluster group call, the uplink service physical channel resources are time-division multiplexed by the users in the group. During a time period when a certain user speaks, these uplink physical resources are enjoyed alone by the speaking user. The downlink service physical channel resources are shared by all listening users in the group during the conversation of cluster group. In a cell, the physical resources between different groups are enjoyed alone.
The cluster system is often used in the domains, such as, meeting an emergency, job scheduling, traffic guidance, etc. In the usage procedure of the cluster UE (User Equipment) application, the cluster UE often moves from a cell to another cell. In the cluster system, the physical channel resources are divided by groups, and different physical channel resources are allocated to different groups. For the physical channel resources allocated to the same group, all UEs in this group share the physical channel. The uplink physical channel resources are enjoyed alone by the speaking user, and the downlink physical channel resources are shared by listening users in the group. The network side is unable to distinguish every UE, so it sends the handover message to every UE respectively.
Thus, there is a problem that the cluster UE cannot hand over the cell freely in the movement process in the relevant cluster system.